In prewinding type cameras, including many of the so-called "single-use" cameras, a filmstrip is initially prewound from a film cassette which is loaded into a film cassette chamber located in the rear of the camera body onto a takeup spool which is loaded into a film roll chamber oppositely situated across from an exposure gate. The filmstrip is then incrementally exposed at the exposure gate an image frame at a time, and rewound back into the film cartridge.
In known takeup spools, such as those described in commonly assigned U.S. Pat. No. 4,852,821, the leader portion of a filmstrip is introduced and retained within a slotted portion of the spool core, while the remainder of the film is subsequently wound onto the outer peripheral surface of the spool. In spools of this type, an integral tooth-like member is used to retain the leader portion within the slotted core. As the leader portion of the film is unwound from the spool, in order to store all of the film within the confines of the lighttight film cassette, however, it is required that the tooth-like member be broken. Thereafter, the spool cannot be reused without some modification or repair. The preceding aspect is significant, in light of present economic and environmental concerns where it is generally preferred that the spool, like other parts of the camera, be made reusable.
In addition, the trailing end of the leader portion of the film is permanently bent when the film is wound and subsequently unwound from the slotted core of the spool, making later removal of the filmstrip from the film cartridge difficult. This is a persistent problem for the photofinisher trying to unload the film because the deformed end of the leading portion makes removal of the filmstrip from the cartridge door difficult.
Reusable takeup spools, such as those disclosed in U.S. Pat. No. 4,930,712, provide a film catching hook on the outer periphery of the spool core, for engaging a perforation of the leader portion of the film, rather than providing means for engaging the leader portion in the slotted core. Though the attachment of the film to the spool is made easier by the inclusion of an outer film hook, the trailing end of the filmstrip is still caused to bend or otherwise deform during unwinding of the film from the spool, still making later removal of the film from the film cartridge difficult.
Therefore, there is a need to provide a takeup spool, preferably for single-use, but usable in other types of cameras as well, which provides for ease of film attachment and detachment without significant deformation of the trailing end of the filmstrip.